diff --git a/SocketStudy/ClientForm/MainForm.cs b/SocketStudy/ClientForm/MainForm.cs
index d1720b2..bb26f86 100644
--- a/SocketStudy/ClientForm/MainForm.cs
+++ b/SocketStudy/ClientForm/MainForm.cs
@@ -17,7 +17,7 @@ namespace ClientForm
 {
 	public partial class MainForm : Form
 	{
-		private readonly string SERVER_IP = "10.233.96.172";//"124.56.13.173";
+		private readonly string SERVER_IP = "124.56.13.173";//"10.233.96.172", "124.56.13.173";
 
 		private PClient heartBeatClient;
 		private PClient client;
diff --git a/SocketStudy/PComm/PClient.cs b/SocketStudy/PComm/PClient.cs
index cea7c10..cd3ee6e 100644
--- a/SocketStudy/PComm/PClient.cs
+++ b/SocketStudy/PComm/PClient.cs
@@ -16,7 +16,6 @@ namespace PComm
 	public class PClient
 	{
 		private readonly int BUFF_SIZE = 1000 * 50; // 50kB
-		private readonly int LARGE_DATA_SIZE_THRESHOLD = 1000 * 50; // 50kB
 
 		public delegate void ClientReceivedHandler(PClient sender, PDataType dataType, byte[] data);
 		public event ClientReceivedHandler OnReceived;
@@ -40,6 +39,8 @@ namespace PComm
 				id = Guid.NewGuid().ToString();
 
 			socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+			socket.ReceiveBufferSize = BUFF_SIZE;
+			socket.SendBufferSize = BUFF_SIZE;
 			this.ID = id;
 			this.EndPoint = new IPEndPoint(IPAddress.Parse(ip), port);
 
@@ -52,6 +53,8 @@ namespace PComm
 				this.ID = Guid.NewGuid().ToString();
 
 			socket = accepted;
+			socket.ReceiveBufferSize = BUFF_SIZE;
+			socket.SendBufferSize = BUFF_SIZE;
 			this.EndPoint = (IPEndPoint)socket.RemoteEndPoint;
 
 			socket.BeginReceive(new byte[] { 0 }, 0, 0, 0, AcceptCallback, null);
@@ -60,7 +63,11 @@ namespace PComm
 		public void Connect()
 		{
 			if (socket == null || !socket.Connected)
+			{
 				socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+				socket.ReceiveBufferSize = BUFF_SIZE;
+				socket.SendBufferSize = BUFF_SIZE;
+			}
 
 			try
 			{
@@ -100,8 +107,8 @@ namespace PComm
 				}
 				else
 				{
-					Debug.WriteLine($"[ERROR] Socket close {socket.RemoteEndPoint.ToString()}");
-					PFileManager.Instance.WriteLog($"[ERROR] Socket close {socket.RemoteEndPoint.ToString()}");
+					Debug.WriteLine($"[ERROR] Socket close {this.EndPoint.ToString()}");
+					PFileManager.Instance.WriteLog($"[ERROR] Socket close {this.EndPoint.ToString()}");
 
 					Close();
 
@@ -173,15 +180,11 @@ namespace PComm
 				socket.Receive(sizeBuff, sizeBuff.Length, SocketFlags.None);
 				int dataSize = BitConverter.ToInt32(sizeBuff, 0);
 
-				// if data size is large, ready to receive data;
-				if (dataSize >= LARGE_DATA_SIZE_THRESHOLD)
-				{
-					int factor = dataSize / LARGE_DATA_SIZE_THRESHOLD;
-					int gain = factor > 10000 ? 10000 : factor;
-					Thread.Sleep(gain);
-				}
+				// if data size is larger than buff size, ready to receive data;
+				if (dataSize >= BUFF_SIZE)
+					Thread.Sleep(100);
 
-				using (MemoryStream ms = new MemoryStream())
+				using (MemoryStream ms = new MemoryStream(dataSize))
 				{
 					while (dataSize > 0)
 					{
@@ -193,6 +196,7 @@ namespace PComm
 
 						int receiveSize = socket.Receive(buff, buff.Length, SocketFlags.None);
 
+						// Thread.Sleep(1);
 						ms.Write(buff, 0, buff.Length);
 						dataSize -= receiveSize;
 					}